Section 6 Target Tracking and AIS 6-34
6.5.7 Setting target for which ground is fixed to a
reference target
By tracking the target for which ground is fixed and setting it to a reference target, the speed of the own
ship can be obtained and displayed.
Note
• The reference target function is to be used if the own ship's speed cannot be displayed
normally due to trouble such as a speed sensor malfunction. Do not use the reference target
function except in emergencies.
• If the speed or course of the own ship is changed or a new reference target is set, the
displayed speed may take 3 minutes or more to reach the specified speed after the
speed/course change or the setting.
Even after 3 minutes or more has passed, the speed may differ from the specified speed
depending on the tracking condition.
• If a large radar echo such as a land target is set as a reference target, the vectors of the
speed and other tracking targets will not be displayed correctly and may cause an accident.
• If a sailing ship is set as a reference target, the vectors of the speed and other tracking targets
will not be displayed correctly and may cause an accident.
• If the reference target is lost or the Target Tracking function is stopped, the ship speed against
the ground will be GPS. (Only if the GPS is equipped.).
• If the reference target is lost or the Target Tracking function is stopped, that will make a major
impact on the accuracy of the target tracking and the own ship speed.
• The reference targets are only used for the calculation of true speed.
• Do not use own speed based on reference target tracking for relative speed and CPA/TCPA
calculation of AIS targets because the response of own speed is slower than actual own
ship's speed change and it may cause a big error on the collision judgement of AIS targets.
1 Acquire the ground-fixed target.
2 Click the right button on the acquired target.
A context menu is displayed.
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